Just for a testing purpose I used Xen almost a year to consolidate my dedicated server, initially dual core and now quad core. First I used Xen VM migration feature which was allowed me to have a separate solution on a server to use DEV. After switching to Core2Duo, I took an advantage of virtualization for consolidation and disconnected the the four large machines that are now just more than a small NAS.
Recently, I decided to upgrade to a Core2Quad before the technology changed. Even though the principle defined for motherboard / cpu to 45nm demands high end servers.
During this change of hardware, I didn’t really expect that at one stage I will have to abandon Xen. Actually, while installing an OpenSuse 11.3, I found myself on a completely unstable system under Xen ( without VM ) which crashed when tens or hundreds of data have been transformed over the network. So finally I opted a more revolutionary solution – qemu-kvm hypervisor, based on its classic nature.
The migration wasn’t too difficult, as Xen & KVM work with a logical drive in a file. So I’ve had to modify the kernel to include a core as a “default” to reboot the system under qemu. In addition, using YaST tools to manage these Vms were simple and easy to use to create an example of VM description in XML format.
Since all of my VM work properly, what I’ve noticed, the configuration options in KVM are somewhat richer than that of Xen. By the way, all these tests tell me that a kernel module should be addressed in KVM, because Xen already shows a certain lack of stability and its implementation is also more complex than KVM.
On Linux, there are applications like kernel (Xen, KVM) allows you to do virtualization on a dedicated server system; a set of applications, especially shared by “box” operating systems which is completely independent of one and other, manage by a “master” for the resource control of each. You can share resources with operating systems so you can create multiple virtual accounts on the same physical server.
The advantage in case of malfunction of your virtual dedicated server is handling the system for maintenance with direct access to storage space to repair it. The whole point of virtual actions to manage through a web interface or ssh to reboot your server instantly.
Applying Xen is available in official package on different Linux distributions, especially on the “Debian Squeeze.” It sets up easily, of course after reading the technical documentation available on the Internet. Hosting companies offer virtual dedicated server solutions pre-configured with a pool of pre-assigned IP on your XEN dedicated server.
The advantage of the hosting virtual application server on dedicated box is; it increases the utilization capacity of resources of dedicated server. With important energy savings, cost effective hosting infrastructure network and server capability able to satisfying customers need, because it is not necessarily to develop the power of resources with this solution. However, when your sites reaches at the limits you will have to consider next level solution.